newlines stripped from captured output

[troelskn]

Hi

I'm trying to write a shell script, which calls an eternal command, that outputs multiple lines. I can capture the output with VAR=$(foobar) (where foobar is the external command), but all the lines are concatenated into a single line. Is there any way to capture newlines as well?
Alternatively, is there a way to pipe the output of one command into stdin of multiple commands?

[ghostdog74]

how does $VAR look like now? and what do you expect it to appear as?

[wje_lf]

troelskn wishes to pipe the output from one program to each of two or more other programs, while running the original input program only once.

Let's call the original program fred.sh:

#!/bin/bash

for ((jndex=0; jndex<10; jndex++))
{
  echo "x$jndex  y$jndex"   # notice the two spaces before the y
}

The output from that program is this:

x0  y0
x1  y1
x2  y2
x3  y3
x4  y4
x5  y5
x6  y6
x7  y7
x8  y8
x9  y9

troelskn wishes to feed those ten lines to each of two other programs. Let's use rev as one of these programs; if we do this

fred.sh | rev

we get

0y  0x
1y  1x
2y  2x
3y  3x
4y  4x
5y  5x
6y  6x
7y  7x
8y  8x
9y  9x

Let's use grep -n ^ as the other program; if we do this

fred.sh | grep -n ^

we get

1:x0  y0
2:x1  y1
3:x2  y2
4:x3  y3
5:x4  y4
6:x5  y5
7:x6  y6
8:x7  y7
9:x8  y8
10:x9  y9

But we can't just do

fred.sh | rev
fred.sh | grep -n ^

because troelskn wants to run the input program only once. troelskn tried the following, I'm sure, because that's what would have triggered his question:

#!/bin/bash

var=$(fred.sh)

echo === begin variable
echo $var
echo === end variable

echo piping through rev:
echo $var | rev
echo piping through grep -n ^:
echo $var | grep -n ^

troelskn's problem is that all the data from fred.sh would be gathered on one line. The output from this program is:

=== begin variable
x0 y0 x1 y1 x2 y2 x3 y3 x4 y4 x5 y5 x6 y6 x7 y7 x8 y8 x9 y9
=== end variable
piping through rev:
9y 9x 8y 8x 7y 7x 6y 6x 5y 5x 4y 4x 3y 3x 2y 2x 1y 1x 0y 0x
piping through grep -n ^:
1:x0 y0 x1 y1 x2 y2 x3 y3 x4 y4 x5 y5 x6 y6 x7 y7 x8 y8 x9 y9

There are two obvious solutions to this problem. One is if you're fairly sure that you can fit all the data into memory at the same time, as would be the case here. Then you can do this:

#!/bin/bash

fred.sh | {
  while read
  do
    array[${#array[@]}]=$REPLY
  done

  echo === begin array
  for ((xxx=0; xxx<${#array[@]}; xxx++))
  do
    echo "${array[$xxx]}"
  done
  echo === end array

  for ((xxx=0; xxx<${#array[@]}; xxx++))
  do
    echo "${array[$xxx]}"
  done | rev

  for ((xxx=0; xxx<${#array[@]}; xxx++))
  do
    echo "${array[$xxx]}"
  done | grep -n ^
}

But if there is much data, you can always punt and put it in a scratch file:

#!/bin/bash

fred.sh > scratchfile

echo === begin array
cat scratchfile
echo === end array

rev < scratchfile

grep -n ^ < scratchfile

rm scratchfile

In either case, the output is:

=== begin array
x0  y0
x1  y1
x2  y2
x3  y3
x4  y4
x5  y5
x6  y6
x7  y7
x8  y8
x9  y9
=== end array
0y  0x
1y  1x
2y  2x
3y  3x
4y  4x
5y  5x
6y  6x
7y  7x
8y  8x
9y  9x
1:x0  y0
2:x1  y1
3:x2  y2
4:x3  y3
5:x4  y4
6:x5  y5
7:x6  y6
8:x7  y7
9:x8  y8
10:x9  y9

Hope this helps.

[troelskn]

troelskn wishes to pipe the output from one program to each of two or more other programs, while running the original input program only once.

Exactly.

Hope this helps.

Very much. Thanks for the detailed reply.